Synthesis of 8-arylated catechin and epicatechin derivatives via Suzuki cross-coupling

8-Arylated catechin and epicatechin derivatives have been prepared in good to excellent yields via Suzuki cross-coupling in the presence of Pd₂(dba)₃ as the Pd(0) source and Sphos as the phosphine ligand.     

Chemoselective and efficient carbomethoxylation of the alcoholic chain of phenols by dimethyl carbonate (DMC)

The efficiency of dimethyl carbonate (DMC) as chemoselective carbomethoxylating agent of the alcoholic chain of phenols has been investigated. In the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or sulfuric acid as catalysts, new carbomethoxylated phenolic compounds were obtained in quantitative yields. A new efficient derivatization of the aliphatic alcoholic chain of the precious natural hydroxytyrosol is described, which increases the lipophilicity of the hydroxytyrosol. The antioxidant activity of this new carboxymethylated hydroxytyrosol 8 has been investigated using DPPH radical scavenging test. The results showed that this new compound has an antioxidant activity similar to hydroxytyrosol.     

Natural Polyphenols as Immunomodulators to Rescue Immune Response Homeostasis: Quercetin as a Research Model against Severe COVID-19

The COVID-19 pandemic is caused by SARS-CoV-2 and is leading to the worst health crisis of this century. It emerged in China during late 2019 and rapidly spread all over the world, producing a broad spectrum of clinical disease severity, ranging from asymptomatic infection to death (4.3 million victims so far). Consequently, the scientific research is devoted to investigating the mechanisms of COVID-19 pathogenesis to both identify specific therapeutic drugs and develop vaccines. Although immunological mechanisms driving COVID-19 pathogenesis are still largely unknown, new understanding has emerged about the innate and adaptive immune responses elicited in SARS-CoV-2 infection, which are mainly focused on the dysregulated inflammatory response in severe COVID-19. Polyphenols are naturally occurring products with immunomodulatory activity, playing a relevant role in reducing inflammation and preventing the onset of serious chronic diseases. Mainly based on data collected before the appearance of SARS-CoV-2, polyphenols have been recently suggested as promising agents to fight COVID-19, and some clinical trials have already been approved with polyphenols to treat COVID-19. The aim of this review is to analyze and discuss the in vitro and in vivo research on the immunomodulatory activity of quercetin as a research model of polyphenols, focusing on research that addresses issues related to the dysregulated immune response in severe COVID-19. From this analysis, it emerges that although encouraging data are present, they are still insufficient to recommend polyphenols as potential immunomodulatory agents against COVID-19.     

Fruit Wastes as a Valuable Source of Value-Added Compounds: A Collaborative Perspective

The by-products/wastes from agro-food and in particular the fruit industry represents from one side an issue since they cannot be disposed as such for their impact on the environment but they need to be treated as a waste. However, on the other side, they are a source of bioactive healthy useful compounds which can be recovered and be the starting material for other products in the view of sustainability and a circular economy addressing the global goal of “zero waste” in the environment. An updated view of the state of art of the research on fruit wastes is here given under this perspective. The topic is defined as follows: (i) literature quantitative analysis of fruit waste/by-products, with particular regards to linkage with health; (ii) an updated view of conventional and innovative extraction procedures; (iii) high-value added compounds obtained from fruit waste and associated biological properties; (iv) fruit wastes presence and relevance in updated databases. Nowadays, the investigation of the main components and related bioactivities of fruit wastes is being continuously explored throughout integrated and multidisciplinary approaches towards the exploitation of emerging fields of application which may allow to create economic, environmental, and social value in the design of an eco-friendly approach of the fruit wastes.     

Interferometric technique for the determination of thermal nonlinearities in semiconductor glasses

An experimental method for the determination of thermal nonlinearities of semiconductor doped glasses induced by cw laser radiation is presented. An estimation of the intensity dependent refractive index is given, at steady state conditions, which is in good agreement with experimental data reported in the literature for similar materials.     

Tyrosyl Radical in the W164Y Mutant of P. eryngii Versatile Peroxidase: an EPR and DFT/PCM Study

Versatile peroxidases (VP) constitute a new class of high redox potential fungal enzymes that are able to degrade lignin and large substrate molecules. These enzymes catalyze the oxidation of substrates at an exposed tryptophan radical formed by a long-range electron transfer mechanism to heme following the activation by H₂O₂. In a previous paper, it was demonstrated using electron paramagnetic resonance (EPR) and electron-nuclear double resonance experiments on wild-type VP that Trp164 was the radical site and that it was in a hydrogen-bonded neutral form. In this paper, the W164Y variant is analyzed and it is shown that also the variant is able to form the so-called Compound I (VPI) in the form of protein radical, although in different yields with respect to the wild type. The X-band EPR experiments in combination with density functional theory/polarizable continuum model calculations show that the W164Y mutant is able to form a neutral radical on Tyr164 residue, after activation by H₂O₂, but in contrast to Trp164, tyrosine is not expected to be hydrogen bonded.     

Climatic factors influencing the isotope composition of Italian olive oils and geographic characterisation

The purpose of this study was to investigate the possibility of identifying oil source areas by means of simple measurements on the natural samples avoiding time‐consuming sample treatments. The oxygen and carbon isotopic values of 150 samples of extra‐virgin olive oil from eight different Italian regions and from three different years of production were measured according to well‐established techniques. Statistical treatments of the results obtained show a very good correlation of the δ¹⁸O of oil with latitude, mean annual temperature, and mean relative humidity at the collection site. No correlation is found with elevation and mean annual precipitation. The shift of the oil δ¹⁸O per degree centigrade of the mean annual temperature is quantitatively close to that calculated for atmospheric precipitation in continental areas. Accordingly, in our measurements, the year of oil production can be identified on the basis of the δ¹⁸O value (mean 2004 temperatures were higher than 2005 temperatures). On the contrary, the oil δ¹³C values show no correlation with the above variables but only with latitude and, consequently, are less suitable for discriminating the geographic origin of oil. However, the δ¹³C values are suitable to indicate biological differentiation while the δ¹⁸O values are not. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of thermal diffusivity of suspended porous silicon films by thermal lens technique

An alumina suspension containing 21 vol.% solids was made to flow through a needle at rates between 10^-12–10^-11 m³s^-1 and was subjected to electrostatic atomization at different applied voltages in the range 5–13 kV. The resulting modes of atomization were studied. The stable cone-jet mode was first obtained at 7 kV and 2.2×10^-12 m³s^-1 and the effect of increasing flow rate and applied voltage on the jet diameter was investigated. Using a pointed ground electrode the alumina droplets produced by the jet in the stable cone-jet mode were printed according to a pre-determined architecture. Alumina relic diameters in the print were <35 m. PACS 81.05.Je; 81.20.Ev; 81.20.Rg; 81.15.Pq; 47.27.Wg